[Magnesium therapy in pregnancy-induced hypertension and pre-eclampsia].

At present, magnesium treatment is employed routinely in the treatment of hypertension induced by pregnancy (PIH) and preeclampsia in USA with the object of preventing seizures. In USA the treatment of election consists of intravenous infusion of large doses of magnesium sulphate in order to obtain a therapeutic concentration. The anticonvulsive mode of action of magnesium is only partially understood. Magnesium is presumed to block the neuromuscular transmission but a central effect cannot be excluded. Treatment with magnesium has, in addition, an antihypertensive effect. The effect of magnesium on the blood pressure is probably a direct vasodilatory effect which explains the ability of magnesium to reduce the maternal blood pressure. Probably the same mode of action is responsible for the relaxing effect of magnesium on the vascular tone in the umbilical and placental vessels. This can probably explain the favourable effect of magnesium on the birth weight. Even if magnesium treatment implies a potential risk for neonatal hypermagnesemia and hypocalcaemia, only few side effects have been reported.